export function downloadFile (file, filename = '') {
  let blob = new Blob([file], {
    type:
      'application/vnd.ms-excel;charset=utf-8'
  })

  let downloadElement = document.createElement('a')
  let href = window.URL.createObjectURL(blob) // 创建下载的链接
  downloadElement.href = href
  downloadElement.download = filename // 下载后文件名
  document.body.appendChild(downloadElement)
  downloadElement.click() // 点击下载
  document.body.removeChild(downloadElement) // 下载完成移除元素
  window.URL.revokeObjectURL(href) // 释放掉blob对象
}
